Simulation and experimental analysis of optimal buried depth of the vertical U-tube ground heat exchanger for a ground-coupled heat pump system

Chen, Jinhua; Xia, Lei; Li, Baizhan; Mmereki, Daniel

doi:10.1016/j.renene.2014.06.007

Cited by 54 publications

(12 citation statements)

References 10 publications

(7 reference statements)

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“…All these parameters are obtained from the laboratory investigations. The physical parameters of four different layers of the soil are the same as shown in Table 2 (Chen et al, 2015;Pu et al, 2015;Li et al, 2006). Fig.…”

Section: Numerical Analysismentioning

confidence: 99%

Laboratory investigations and numerical analysis of thermal performance of the single U-tube VBHE in multiple-layer substrates

Liu

Huang

Yang

et al. 2018

JTST

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In order to study the thermal performance of a single U-tube VBHE in multiple-layer substrates, the similarity principle was used to build an indoor comprehensive miniature bench of single U-tube VBHE innovatively, and effects of inlet water temperature and hydrogeological geology on the thermal performance of VBHE were analyzed. In addition, numerical simulation was used to assist in the research. The results indicate that to build a laboratory-scale GSHP system model test apparatus based on the similarity principle will achieve long-term test of GSHP system with smaller human and material resources and a shorter experimental cycle. It's more efficient and convenient. The simplified use of uniform soil thermal and physical properties can cause great deviation. Heat flux per unit pipe of the VBHE increases linearly with the temperature difference's increasing between the inlet water and initial soil. The water temperature along the tube under thermal conductivity increasing and decreasing conditions does not decrease as linearly as the temperature's decreasing under the uniform thermal conductivity condition.

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Section: Numerical Analysismentioning

confidence: 99%

Laboratory investigations and numerical analysis of thermal performance of the single U-tube VBHE in multiple-layer substrates

Liu

Huang

Yang

et al. 2018

JTST

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“…Ground source heat pump (GSHP) systems are well known as one of the most energy efficient and environmentally friendly technologies and have been widely applied in various buildings around the world [1][2][3]. Solar photovoltaic-thermal (PVT) collectors which combine photovoltaic (PV) panels and solar thermal collectors are able to produce both electricity and thermal energy simultaneously [4].…”

Section: Introductionmentioning

confidence: 99%

A model-based optimal control strategy for ground source heat pump systems with integrated solar photovoltaic thermal collectors

Xia

Kokogiannakis

et al. 2018

Applied Energy

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This paper presents a model-based optimal control strategy for ground source heat pump systems with integrated solar photovoltaic thermal collectors (GSHP-PVT). The control strategy was formulated using simplified adaptive models and a genetic algorithm (GA) to identify energy efficient control settings for GSHP-PVT systems. The simplified adaptive models were used to predict the system energy performance under various working conditions and control settings, and the model parameters were continuously updated using the recursive least squares (RLS) estimation technique with exponential forgetting. The performances of the adaptive models and the control strategy were evaluated based on a virtual simulation system representing a GSHP-PVT system for residential applications. The performance of the major adaptive models was also validated using the experimental data. The results showed that the simplified adaptive models used were able to provide acceptable energy performance prediction. The optimal control strategy can save energy consumption by 7.8%, 7.1% and 7.5%, and increase electricity generation by 4.4%, 6.2% and 5.1%, during the whole cooling, heating and transition periods considered, respectively, in comparison to a conventional control strategy. The findings obtained from this study could be potentially used to drive the development of advanced control strategies suitable for real-time applications.

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“…However, in earlier experimental studies [12][13][14][15] focused primarily on the TC of grout; SHC was usually ignored. Also, the SHC of grouts used in previous numerical analyses varied widely or was not measured [24][25][26][27]. During numerical modeling, invalid inputs may compromise the results.…”

Section: Introductionmentioning

confidence: 99%

Optimizing the Design of a Vertical Ground Heat Exchanger: Measurement of the Thermal Properties of Bentonite-Based Grout and Numerical Analysis

Kim

2018

Sustainability

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We prepared bentonite-based grouts for use in the construction of vertical ground heat exchangers (GHEs) using various proportions of silica sand as an additive, and measured the thermal conductivity (TC) and specific heat capacity (SHC) of the grouts under saturated conditions. Furthermore, we performed numerical simulations using the measured thermal properties to investigate the effects of grout-SHCs, the length of the high-density polyethylene (HDPE) pipe, the velocity of the working fluid, and the operation time and off-time during intermittent operation on performance. Experimentally, the grout TCs and SHCs were in the ranges 0.728–1.127 W/(mK) and 2519–3743 J/(kgK), respectively. As the proportions of bentonite and silica sand increased, the TC rose and the SHC fell. Simulation showed that, during intermittent operation, not only a high grout TC but also a high SHC improved GHE performance. Also, during both continuous and intermittent operation, GHE performance improved as the working fluid velocity increased, and there was a critical working fluid velocity that greatly affected the performance of the vertical GHE, regardless of operation mode, high-density polyethylene (HDPE) pipe length, or grout thermal properties; this value was 0.3 m/s. Finally, during intermittent operation, depending on the operation time and off-time, critical periods were evident when the ground temperature had been almost completely restored and any beneficial effect of intermittent operation had almost disappeared.

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Simulation and experimental analysis of optimal buried depth of the vertical U-tube ground heat exchanger for a ground-coupled heat pump system

Cited by 54 publications

References 10 publications

Laboratory investigations and numerical analysis of thermal performance of the single U-tube VBHE in multiple-layer substrates

Laboratory investigations and numerical analysis of thermal performance of the single U-tube VBHE in multiple-layer substrates

A model-based optimal control strategy for ground source heat pump systems with integrated solar photovoltaic thermal collectors

Optimizing the Design of a Vertical Ground Heat Exchanger: Measurement of the Thermal Properties of Bentonite-Based Grout and Numerical Analysis

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